Things to know about wastewater treatment using biological methods

1. What is wastewater treatment using biological methods?

Biological wastewater treatment is a process that uses microorganisms and natural biological processes to remove or transform pollutants in wastewater into non-harmful or significantly reduced to levels that are safe for the environment. This method takes advantage of the capabilities of microorganisms such as bacteria, viruses, algae, and natural processes such as metabolism and precipitation to treat wastewater.

2. Mechanism of action of biological process in wastewater treatment

The mechanism of action of biological processes in wastewater treatment involves interactions between microorganisms such as bacteria, viruses, algae and natural biological processes to remove or transform pollutants. contamination in wastewater. Some main operating mechanisms of biological processes in wastewater treatment are listed below:

Biodegradation:

Bacteria and other microorganisms in wastewater are capable of processing organic substances such as complex organic substances, grease, proteins and other organic substances. This treatment process usually involves bacteria converting organic substances into products such as CO2, water, simpler organic substances and biological sludge.

Nitrogen and Phosphorus Removal:

Bacteria and other microorganisms are capable of processing nitrogen and phosphorus compounds in wastewater, such as ammonia, nitrates, nitrites and organic phosphorus. The bacteria convert nitrate or nitrite into gaseous nitrogen and the phosphorus bacteria convert phosphorus into biological sludge, which helps to remove these substances from wastewater.

Biological Precipitation:

Bacteria in biological processes can create conditions for pollutants to aggregate into insoluble residues. For example, sulfate-reducing bacteria have the ability to reduce sulfate to sulfide, allowing heavy metals such as iron and multifunctional metals such as selenium to agglomerate into insoluble particles.

Dual Stirred Sludge Biology (Sequencing Batch Reactor - SBR):

The SBR process combines different stages in a single tank, in which bacteria metabolize organic substances, nitrogen and phosphorus. The process is controlled by changing the time and operating cycle of the stages, creating optimal conditions for the biological process.

Constructed Wetlands:

Bioburden uses vegetation and moist environments to provide suitable conditions for bacteria and other microorganisms to metabolize organic matter and remove pollutants such as nitrogen and phosphorus.

The mechanism of action of biological processes often depends on the type of microorganisms present, the environmental conditions such as temperature, pH, amount of dissolved oxygen, interaction mechanism between them and the type of pollutant present in the wastewater. These processes work together in order to minimize the impact of pollutants on the environment and produce better quality treated wastewater.

3. Biological methods for wastewater treatment

3.1 Artificial methods

Biological wastewater treatment systems often include many different steps and components to ensure an effective treatment. Below is an example of the basic structure of a biological wastewater treatment system:

- Pretreatment tank: Input wastewater is often put into a pretreatment tank to remove large impurities, such as garbage, sand, soil and other organic impurities. Pretreatment steps may include mechanical screening, filtering agents, and pH balancing.

- Biological treatment tank: After going through the pre-treatment step, wastewater is put into a biological treatment tank, where biological processes take place to remove pollutants. This tank usually includes different areas with different environmental conditions to create favourable conditions for the growth of bacteria and microorganisms capable of decomposing organic substances.

a. Anaerobic Tank: If the system uses the anaerobic method, the anaerobic tank will have a hypoxic environment to create conditions for anaerobic bacteria to decompose organic matter into methane gas and other decomposition products.

b. Anoxic Tank: In some cases, there may be an anoxic tank to remove other contaminants such as nitrates. The bacteria in this tank will use pollutants instead of oxygen to carry out the treatment process.

c. Aerobic tank (Aerated Tank): Aerobic tank provides oxygen for aerobic bacteria to create conditions for the bacteria to decompose organic matter into water, CO2 and other decomposition products.

- Precipitation and sedimentation tank: After the biological treatment stage, wastewater is put into the precipitation and sedimentation tank to remove remaining suspended impurities. During this process, particles gather and settle to the bottom of the tank.

- Treated water tank: Water that has gone through biological treatment and sedimentation is put into the final tank before being discharged into the environment or reused.

- Control and monitoring system: Wastewater treatment systems are often controlled and monitored using equipment and technology to ensure that the treatment process takes place according to parameters and meets environmental requirements.

The structure of a biological wastewater treatment system can vary depending on the scale and specific requirements of each project.

3.2. Treat wastewater using an ecological system

Ecological pond systems and microbial filtration systems are two wastewater treatment methods that use biological and microbial processes to remove pollutants in wastewater. Below is a detailed description of each method:

Ecological Pond System:

An ecological pond system is a wastewater treatment system that uses the natural environment, including lakes and the plants and animals that live in this environment. Wastewater treatment in an ecological lake system takes place through natural biological processes such as organic metabolism, nutrient absorption by plants, and self-balancing ecological mechanisms.

The wastewater is dumped into lakes in the system, and plants such as algae and bacteria. In the lakes it begins to metabolize the organic matter and to absorb nutrients such as nitrogen and phosphorus. Animals living in the lake also contribute to the treatment process by metabolizing bacterial cells and other organic substances.

Natural ecological processes in the ecological lake system create a balanced environment between plants and animals, helping to remove pollutants and improve wastewater quality.

Biofilter System:

A biological filtration system is a wastewater treatment method that uses bacteria and microorganisms to remove pollutants. This system usually includes a tank filled with filter media such as sand, crushed rock or other types of filter media. In this filter tank, bacteria and microorganisms metabolize organic substances and remove nutrients.

Wastewater is poured into the filter tank and passed through the filter material. Bacteria and microorganisms in the filter media metabolize pollutants as in natural ecological processes. Then, wastewater is drained from the system with a better quality.

Both ecological lagoon systems and biofiltration systems take advantage of the ability of microorganisms and biological processes to remove pollutants and improve wastewater quality. At the same time, they are also methods that can use natural ingredients for the processing, in order to minimizing negative impacts on the environment.

4. Methods of treating wastewater sludge created after biological treatment

Biological sludge treatment is an important part of the wastewater treatment process. Bio-sludge is a by-product of biological processes in wastewater treatment systems, and the management and treatment of bio-sludge ensures that this waste is not polluting and can be safely disposed of. Below are some biological sludge treatment methods in wastewater treatment:

Activated Sludge Treatment:

Biological sludge from an activated sludge system is often treated using a portion of the reused sludge to start bacteria in the next treatment stage. The remaining sludge can be processed through disinfection or discharged into the environment after ensuring that it does not cause pollution.

Sludge treatment with water hyacinth (Sludge Digestion):

Biological sludge treatment with water hyacinth is a popular method to reduce sludge volume and produce useful methane gas. During this process, the sludge is placed in an oxygen-deficient environment to facilitate bacteria processing of the sludge. As a result, the amount of sludge is reduced, and methane gas is produced.

Sludge treatment by incineration technology (Sludge Incineration):

Biological sludge can be burned to reduce its volume and disinfect. This combustion process also generates heat energy that can be used to power the wastewater treatment process.

Sludge treatment using filtration technology (Sludge Dewatering):

The sludge filtration process removes water from the sludge, making it drier and easier to handle. Sludge filtration methods include pressure filtration, belt filtration, frame filtration, and disc filtration.

Sludge Treatment by Anaerobic Digestion:

This process uses decomposing bacteria in an oxygen-deficient environment to convert biological sludge. This process does not only reduce sludge volume but also produces methane gas that can be used as an energy source.

Biological sludge treatment ensures that biological sludge from wastewater treatment does not cause pollution and can be managed, treated and disposed of safely and effectively.

Used in sludge treatment from wastewater treatment tanks

Sludge treatment is an important part of the wastewater treatment process, to ensure that biological sludge is managed and treated safely, does not cause pollution and can be used or disposed of effectively. Below are common applications of sludge treatment from wastewater treatment tanks:

Sludge Reuse:

Sludge from wastewater treatment tanks can be reused as bacterial starter for wastewater treatment in the next stage. Reusing sludge increases the treatment efficiency and reduces the amount of new sludge created.

Sludge Disposal:

Biological sludge can be destroyed by incineration, sterilization or other treatment methods to reduce the volume and to remove contaminants.

Sludge Treatment and Disinfection:

Sludge from wastewater treatment tanks needs to be treated and disinfected before being destroyed or reused. Sludge treatment methods include high temperature disinfection, chemical disinfection such as chlorine or ozone.

Energy Generation from Sludge:

Bio-sludge can be used to generate energy in anaerobic metabolic processes, producing methane. Methane gas can therefore be used as a combustion or heat source.

Production of Organic Fertilizer:

Sludge after biological conversion can be used to produce organic fertilizer. This fertilizer contains essential nutrients for plants and can be reused in agriculture.

Use in Construction (Use in Construction):

Sludge from wastewater treatment can be used as raw materials in construction projects such as filling soil, building materials, or planting materials in green areas.

These applications ensure that biosludge is not just a pollutant but can also be used and recycled effectively to create value and limit negative environmental impacts.

5. Advantages and limitations of biological methods in wastewater treatment

5.1 Advantages of biological wastewater treatment method

Biological wastewater treatment methods have many important advantages, helping to effectively remove pollutants and improve the wastewater quality. Here are some advantages of biological wastewater treatment:

Sustainability and nature: Biological wastewater treatment methods take advantage of natural biological processes and use microorganisms to metabolize pollutants. This creates a sustainable and balanced processing environment with nature, minimizing negative impacts on the environment.

High efficiency: Biological wastewater treatment method can achieve high treatment efficiency in removing organic substances, nitrogen, phosphorus and other pollutants from wastewater. Microorganisms in biological processes can metabolize these substances effectively.

Energy savings: Some biological wastewater treatment methods, such as anaerobic metabolism and water hyacinth sludge treatment, can produce methane gas that can be used as an energy or heat source. This helps to reduce the energy consumption from traditional energy sources.

Reducing the amount of sludge and wastewater volume: Biological wastewater treatment methods help to reduce the amount of sludge generated during treatment and can remove some of the water from the sludge, making the sludge drier and easier to handle.

Creating value from by-products: Bio-sludge created during wastewater treatment can be recycled and used to produce organic fertilizer or generate energy. This creates value from by-products and reduces processing costs.

No need to use chemicals: Biological wastewater treatment does not require the use of chemicals to remove pollutants. Instead, it relies on natural and microbial processes to treat wastewater.

Biological wastewater treatment offers many advantages in terms of performance, sustainability and energy savings, while reducing negative environmental impacts and creating value from by-products.

4.2 Disadvantages of biological wastewater treatment methods

Although biological wastewater treatment has many advantages, there are also some disadvantages that need to be considered. Here are some disadvantages of biological wastewater treatment methods:

Space consuming: Some biological wastewater treatment methods, such as ecological pond systems and microbial filtration systems, require large areas to deploy. This can make it difficult to find enough space to build treatment systems.

Long treatment times: Biological wastewater treatment methods often require longer treatment times than some chemical or mechanical wastewater treatment methods. Bacteria and microorganisms need time to metabolize pollutants in wastewater.

Requires specialized knowledge: Implementing and managing biological wastewater treatment systems requires specialized knowledge of microorganisms, ecology, and wastewater treatment techniques. This can create a challenge for training and retaining personnel with the necessary skills.

Ability to be affected by environmental conditions: The performance of biological wastewater treatment methods can be affected by changes in environmental conditions such as temperature, pH, and the amount of sunlight. This may reduce the processing performance in some cases.

Needs of regular management and maintenance: Biological wastewater treatment systems need to be regularly managed and maintained to ensure that they operate effectively. This includes testing for microorganisms, to ensure the correct wastewater flow and providing good conditions for biological processes.

Inability to respond adequately in emergency situations: In emergency situations or when the need for wastewater treatment suddenly increases, biological wastewater treatment methods may not be adequate and require time to enhance the performance.

Biological wastewater treatment has its own disadvantages, but when properly designed, implemented and managed, it is still an effective method in improving wastewater quality and protecting the environment.

6. Practical application of biological methods in wastewater treatment

Biological wastewater treatment methods have many practical applications in treating and improving wastewater quality. Below are some examples of practical applications of biological wastewater treatment:

Municipal wastewater treatment systems: Cities and urban areas use biological wastewater treatment systems to remove pollutants from wastewater before it is discharged into the environment. These systems include ecological ponds, biofilters, and activated sludge systems to convert organic matter and nutrients.

Industrial wastewater treatment plants: Factories and industrial production facilities often use biological wastewater treatment methods to remove pollutants from industrial wastewater. This helps to prevent the discharge of polluted wastewater into the natural environment.

Farm wastewater treatment: Farms and agricultural areas use biological wastewater treatment methods to minimize the negative impacts of wastewater from agricultural operations. This treatment system can reduce the amount of nutrients and other pollutants from wastewater before it is released into the environment.

Wastewater treatment systems at tourist areas and resorts: Tourist areas and resorts often use biological wastewater treatment methods to treat wastewater from tourism activities and to reduce the impacts on the local environment.

Wastewater treatment from the food industry: The food industry often uses biological wastewater treatment to remove organic substances, nutrients and impurities from production wastewater.

Wastewater treatment systems in remote residential areas: In areas that are remote or do not have traditional wastewater treatment systems, biological wastewater treatment methods can be used to ensure that wastewater does not pollute the surrounding environment.

These practical applications indicate that biological wastewater treatment methods have been widely applied in various fields to minimize the negative impact of wastewater on the environment and to improve the wastewater quality.

Biological treatment methods often take advantage of natural biological processes and do not require the use of chemicals. This can be an environmental benefit and reduce negative impacts on the surrounding environment. In addition to biological wastewater treatment, there are also chemical wastewater treatment methods and physicochemical wastewater treatment methods . The choice of the wastewater treatment method should be considered based on the nature of the wastewater, performance requirements, finances, space, management capabilities and other factors. These factors should be integrated to make an appropriate decision.